If you worked through the Cookbook item Just enough Erlang/OTP and rebar, part 1, you have
created two Erlang applications under management of Rebar. You’ve used
Rebar to create a gen_server template in the first application and
added several functions. You’ve also created a library application
with one function.

You should see a graphic window open with a list of running
processes. Find zzz_srv and zzz_sup under Name. Click on
zz_sup to highlight. Now pull down the Trace menu item and click on
kill. Note that you’ve not only killed zzz_sup, but zzz_srv as
well. Of course. zzz_sup supervises zzz_srv. When it dies, so does
zzz_srv.